The present invention is a portable map display device allowing the user to display on a built-in rear projection screen a frame from a microfilm fiche module representing a road map, a navigation chart, or the like.
In the course of a long cross-country journey, it is not uncommon for a motorist to carry along a plurality of road maps and city maps which he must consult from time to time in order to determine the best available itinerary from one location to another, to compute distances and the time required to travel from one location to another. Conventional road maps, printed on paper, are awkward to handle, difficult to refold along the original folding lines, cumbersome when unfolded, and cities, villages or other sites are difficult to identify even when referring to a directory giving a list of such cities, villages and sites by reference to numerical and alphabetical coordinates. In addition, it is difficult for a motorist on the go to trace an appropriate itinerary on a paper map, and to determine at a glance his location along that itinerary.
Diverse attempts have been made in the past to replace conventional, foldable maps and charts by maps in the form of scrolls which are manually unrolled or which are, preferably, placed in a housing provided with a viewing window. The scroll is attached at each end to a winding and unwinding rod such as to allow unrolling the map flat under the window. However, such an arrangement requires a substantially cumbersome device, and requires fastidious manipulations every time the map must be replaced by another.
The inconveniences and shortcomings of the prior art are overcome by the portable map display device of the present invention which permits to project on a viewing screen a single frame from a microfilm fiche module, the microfilm fiche module providing as much information as would otherwise be provided by a plurality of conventional foldable road maps. Any appropriate individual frame representing a single map, or a portion of map, can be manually indexed such that a predetermined map may be projected on a viewing screen built into the device. As each fiche module is the equivalent of, for example, twenty or thirty, or more, individual maps, a few of such fiche modules are sufficient to cover a considerable territory, by simply replacing the microfilm fiche module in the device of the invention by another.